78 High School Kid Build

Discussion in 'The Stable' started by Thad Turner, Jun 5, 2018.

  1. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Not trying to be an ass, but how would Summit know what bearings you need?
    You need to know the crank journal size and the size of the rod openings.
    They can give you stock bearings that should work if the engine has never been touched and has all original parts, but that is all they can do.
    It is required that a plastigauge check be done of the installed bearings even if everything is stock to verify clearances, starting with the crank bearings. Part goes on with plastigauge installed, torqued, plastigauge checked, if good, assembly lube, then next bearing until all are installed.
    A little time and some cheap plastic strips will save you from the risk of collecting engine parts off the road down the line.
     
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  2. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    One of the first lessons I learned in assembling a freshly-machined engine (not necessarily "engine building") is you trust but verify. You certainly either trust the machine shop you go to, otherwise you wouldn't have gone there, but we're all human, we make mistakes, so verification of the machinist's work is necessary when putting an engine together, in order to find those problems that pop up once in a while. You get the engine rebuilt, and have the machine shop obtain the rebuild kit, they give the supplier the dimensions on the bearing surfaces and the main and rod bearing bores. If you buy your own parts, you get the dimensions from the machinist and tell them to your supplier, then, as John said, you assemble with Plastigage, measure the squished Plastigage, and if the squished width is within the machining tolerance, you lube the bearing shells and assemble/torque. I did my 351W as follows (no boo birds, please): I laid out the block shells, laid down the crank, then laid out the cap shells, torqued down all the caps, then took all the caps off and measured. IIRC, the mains were all the same, so i pulled the crank, liberally lubed everything, placed the caps, set the thrust and torqued it down. Rods you can do one at a time, and each one I did, once it was liberally lubed and properly assembled, I gently turned the crank to verify it wasn't locked up. BTW, a couple things that can hold the crank from turning is a backward cap, or two out-of-place caps. It's why properly marking both the cap and rod are so important.
     
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  3. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    Yikes... Well I feel like I've done everything all wrong. So let me get this straight.

    If my connecting rod journal was 2.3103 inches and my oil clearance should be 0.009 inches then the diameter of my bearing inside the rod torqued down should be at least 2.3112 inches? Is that the correct thinking? And so I need to go to a machine shop with equipment to measure things like that to get me the correct bearing thickness? Is that at least the correct logic as to what's happening?

    Edit: I do have plastigauge and after using it it appears that the oil clearance is way too tight. So I need bearings that aren't as thick as the ones I got from Summit?
     
  4. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Borrow or rent a micrometer and measure the bearings you received to make sure they are to spec.
    Is there any chance that you mixed up the connecting rod caps? Or installed any of them backwards? They are honed assembled and have to go back together exactly as they came apart.
    The rod ID should not be any different (other than a thou or so) hand assembled, or properly torqued.
    Due to the difficulties in accurately measuring round objects the math approach is risky. Best to take a plastigauge on an old bearing and measure that bearing in a few different places. Don't forget that a bearing 2 thous thicker will reduce the hole by 4 thou
     
  5. Thad Turner

    Thad Turner In Second Gear

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    67
    Would a dial caliper work? I have a few precision instruments like that. I know for sure that the rod caps are on the same rod they came off of but I suppose there could be a chance they are on backwards. Should the notch that the bearing sit in be on the same side or opposite side as the rod from the cap? If that doesn't make sense I can take a picture. I believe I have them correct.

    I will go ahead and plastiguage the old bearing and get that number back to you.
     
  6. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Most caps are difficult to install backwards, I just try to cover every possibility.
    A dial caliper can be used if it is in real good shape and has a knife edge. Lay the bearing on a flat surface with the caliper clamped perpendicular to the bearing and true to the surface the bearing is placed on and slide in to the same point (make sure you mark the bearing where the plastigauge was inserted) as the plastigauge was installed. Have the bearing loose, the knife edge on the inside of the bearing. That way you will have a jig that can make repeatable measurements.
     
  7. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    Here is what the plastigauge looks like with the old bearing

    [​IMG]

    Here's what it is with the new bearing

    [​IMG]

    [​IMG]

    The reason I show you this is because they are both obviously way tighter than 0.009 and the oil clearance is supposed to be between 0.008-0.0026. I need to get the blue plastigauge I suppose to see EXACTLY what it is. But they're obviously both way too tight... except the old bearing has been worn like nobody's business, so why is it still too tight around the oil clearance? Unless the yellow plastigauge is simply way too inaccurate once you're tighter than 0.009. With these pictures does that change anything? The worn bearing was still just as tight on the plastigauge.
     
  8. Freestyle Don

    Freestyle Don In Third Gear BRONZE MEMBER

    Messages:
    166
    I gotta chime in here.....MEASURE THE CRANKSHAFT! How did you know which bearing to order??
    I was in the crankshaft grinding business for 38 years and have seen a lot of folks `rebuilding` engines that perhaps shouldn`t have. The tolerances between crankshaft journals and bearings are less than the thickness of a hair. In the BEST case scenarios .002! The suggestions here are all good, however you should have someone experienced with engine rebuilds and micrometer reading feels check for you. In addition, I have had folks bring me a crankshaft and a box of rods and caps tossed in, not matched. It takes some time but you can trial and error match in most cases. Remember rods and caps are a matched pair! Worst case, have them properly resized at a machine shop. Well worth it as you are working on the most technical part of your rebuild.
     
  9. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    I understand this is certainly a complicated business but you've gotta learn somewhere right?... My caps all go on nice and smooth. I know for sure they're with the correct rod and by the way they come on and off I'm pretty confident they're in the correct orientation. My only problem has been that the oil clearances between the bearing and the journals is simply too tight. Back in one of my previous posts on this thread I wrote the oil clearances for the bearings, 0.0008-0.0026, and that's the same for both the main bearing and rod bearings. So shouldn't I have a clearance about that size when I plastigauge the journals?

    Once I get the measurements of the journals and openings on the block and rods I should be able to order bearings that will be custom made for my engine?
     
  10. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Not "custom-made," but correctly-sized. You need to measure the crank journals to ensure the crank was correctly-ground. That grinding, called the "undercut," is made to match bearings made for that undercut only.
    For example, say your crank has 3.500 main and 2.750 rod journal sizes from the factory. And now you have to have the mains and journals ground because of wear on them. If the wear is light, it's possible to get a .005" undercut in order to leave as much material in the journals as possible, but a standard undercut is .010". So, as long as you haven't radically altered the crank from the 3.500" main and 2.750" rod journal sizes you should be able to order the bearings for a specific engine in a specific model year with those specific sizes cut .010 under, have ones available for fitting a .010 undercut, and they should work. That's why you verify the journal sizes. With the crank correctly ground and the correct bearings, the oil clearance should fall into place.
     
    Freestyle Don likes this.
  11. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    8,244
    Location:
    Everett, WA
    Have you pulled out one of the rod bearing shells and looked to see if the backside indicates an undercut? It will be on the outside, under the locating tang.
     
  12. ribald1

    ribald1 Banned PLATINUM MEMBER

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    A cut crank will yield more clearance, not less.
    The pictures didn't come through. What do the gauges say the clearance is?
     
  13. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Right. But an uncut crank with a bearing meant for a cut crank would lock it up.
     
  14. Freestyle Don

    Freestyle Don In Third Gear BRONZE MEMBER

    Messages:
    166
    Try this. With the caps and rods. One at a time. With no bearings, put caps on loose. No need for nuts or torqued You should not feel the parting line when properly matched. If you do, they are not a matched pair.
     
  15. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    Caps were on backwards. The motor will be taken to my machine shop this weekend for a hot bath and when I get it back it will be ready for reassembly.
     
  16. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    It's good you found that. I see this as your first positive learning experience. You ran into a problem, you brought it to us, we explained things to you, hopefully without confusing you, you identified the problem, and solved it.
     
  17. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    Oh just the first of many XD thanks guys
     
  18. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Yah velcome!
     
  19. Thad Turner

    Thad Turner In Second Gear

    Messages:
    67
    Update

    I haven't been around for awhile mainly because of the motor being at the machine shop and my work and school going into full swing, but I figured I'd show you guys where I am currently and some future stuff.

    I had the block dipped and the crank checked and polished. Everything was good to go so I had my main bearings put on and it turns as smooth as glass now. Oddly satisfying.

    [​IMG]

    [​IMG]

    [​IMG]

    And I also spent the money to get the rest of the parts I need for this 351 rebuild, the rings and oil pump should be here tomorrow. I have cam bearings and I'll have those put in along with freeze plugs sometime this week I believe.

    [​IMG]

    Then it will be to reassembly with my gear drive that arrived just the other day.

    [​IMG]

    Since I'll be waiting awhile before the engine will be completely reassembled I decided to start on the Edlebrock 14005 rebuild, and now it's all in a billion parts.

    [​IMG]

    And I will need to get the bucket of fluid that you dip the carb parts in, so until then I believe I will be giving the intake some love.

    [​IMG]

    So while I wait on cam bearings and freeze plugs for the block and carb cleaner for the carb, that intake will be painted and I will continue body working the hood. But for some future things, I got a great deal on a pair of sub woofers and so I know where I'll start with my sound system, sadly the sound system won't happen until the floor pans are done and I can start to work the interior but in the mean time I'll work on the boxes and planning the rest of it. And also I got a great deal on a C6 transmission. I plan to go big block with a 460 eventually so I will need a C6 and it was a really good deal so I figured I'd grab it and then grab the 460 whenever I see a good deal on one of those. That's pretty far in the future and I want to get a couple hundred miles on this 351 first. So once the 351 is done I'll be going through that C6 to make sure it's nice and straight, maybe even build it. But for now I'll stick with my 351 and C4 and work on the body and the interior. When the 460 build happens I plan to go to EFI and some sort of forced induction, probably turbocharging but that's way too far into the future to be worrying about now. Goodnight y'all.

    [​IMG]

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    [​IMG]
     
  20. ribald1

    ribald1 Banned PLATINUM MEMBER

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    Location:
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    Put assembly lube on all the surfaces yesterday! Also, put light oil on a rag and wipe the inside of the cylinders.
    You are making good progress, don't let a missing detail derail all your hard work down the road.
    Also, carefully check the gear drive clearance with the cover. The oil diverter always interferes, and casting tolerances are rather high. You don't want it clearanceing itself and dumping the excess metal into the pan and the gears of the gear drive.
    Also check cam end play with the cam gear installed and make sure it doesn't get within 40 thou of the block. Some of those Chinese gear sets are much thicker than the stock gear.
    If you want an easy trick to keep the convertor in place, drill a 1/8" hole in the bottom of the bell housing and pass a string through it. Tie one end to a convertor stud and the other end to the tail. That will keep the convertor from hopping off the pump as you wrestle it into place.
     

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